The improved method of this invention generally involves the injection of certain liquid compositions into the vascular systems of slaughtered animals e.g., cows, steers, bulls, horses, deer, chicken and other poultry, pigs, and so forth as does the method described in U.S. Pat. No. 4,053,963, which issued on Oct. 18, 1977 and the patents referred to therein, all of which are incorporated herein by reference.
In accordance with the instant invention, one aspect of the improved method involves the application of electrical stimulation to the animal upon its being debled. This has several beneficial effects on all varieties of food animals. It is known to increase the tenderness of the meat among other things, as reported in the study entitled Electrical Stimulation for Improving Meat Quality, sponsored by Texas A & M University (TAMU), circa 1978, incorporated herein by reference. However, it has been discovered with respect to the instant invention that electrical stimulation, in combination with the improved injection process, also hastens the circulation of the treatment solution throughout the animal's vascular system in the injection process of this invention. Additionally, it aids in removing the blood from the animal more completely and more rapidly. This shortens the bleeding of the animal from minutes to seconds. It also shortens the time to dehide the animal by minutes. All of this saves plant process time.
Electrical stimulation in combination with the injection process also provides unexpected increases in tenderness and in yield. During its application it may be be applied constantly or intermittently at voltages ranging from about 14 volts to 600 volts, 30 to 40 volts being more typical as reported in the TAMU study identified above.
Instead of introducing the treatment solution through the jugular vein and out the severed hind legs only as described in U.S. Pat. No. 4,053,963, the improved method requires in another of its aspects that all the legs of the slaughtered animals, all four legs in the case of quadrupeds, be severed to allow drainage of the solution from the veins of all four severed legs, i.e., use of all legs as drainage points. Strictly speaking, all that is required is severing of the major blood vessels in all of the legs, not removal of the legs. For example, in a quadruped, one would sever the major veins or vessels in all four legs. However, this is most readily accomplished by simply severing all the legs from the carcass at about the knee joints from a practical standpoint.
Another important effect of utilizing all the legs of the slaughtered animal as drainage points is to make the distribution of the composition more even throughout the meat of the animal.
Another aspect of the inventive method involves use of a cool treatment solution, about 30.degree.-50.degree. F. This "rapid chills" the animal thereby requiring less initial refrigeration time and enhancing the plant's ability to debone and/or butcher the carcass. This allows the plant to debone sooner and saves additional overall plant processing time and it provides a higher yield per animal in the deboning process.
The injection procedure, in another aspect of this invention, has been decontaminated by introducing the use of a self-piercing nozzle tip. The U.S.D.A. has indicated that the method should be made more sterile at this point without increasing processing time. Thus, the earlier technique involving the use of a knife to incise the animal's hide, remove the membrane sheath around the jugular and then slit the jugular, followed by insertion of a blunt nozzle tip for introduction of the treatment solution is no longer desirable. The improved technique, using a self-piercing nozzle tip, solves the contamination problem and additionally saves more plant time, about 1/2 minute per animal in the case of beef, for example. The new nozzle simply pierces the sheath and the vein.